Using a wireless security system

Bald Eagle

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I met a guy a few years ago who said that he was a professional photographer and a computer geek.  He seemed to be in his 60's at that time.  I met him at a resteraunt near one of my favorite hunting woods.  I was trying to get his permission to hunt his land.  It was at the peak of the rut and he owns a 200+ acre woods and he uses it for his photography.  Anyway, he has created a very nice clear path system that cris-crosses the woods.  He keeps it raked down to almost bare soil.  He has 10 photo sensors attached to trees at about 3 ft. off the ground along these trails.  He somehow modified a wireless security system and his laptop computer shows him exactly where there is movement on any of the trails.

I was skeptical of his story until he showed me his laptop out in the parking lot of the resteraunt and invited me to take a walk along one of his trails.  Thinking that I was going to get permission to hunt, I followed to his property and we parked at his trailhead.  His system was really great.  He had a graphic screen showing his land and all the trails.  Pretty neat looking graphic with brown trails and different shades of green for the different kinds of trees and blue for the two lakes and three creeks.  The screen also showed five black squares that indicated his tree blinds and ground blinds.  There was a red circle for each of the motion sensors and each circle would turn bright and blink whenever there was motion in the zone of the sensor.  I am not an expert in electronics so I was very impressed.  We only walked about 150 yards into the woods and one of the red dots started to blink.  Pretty neat.

Well since he was using the land for his photography I did not get permission to hunt.  But I did get a terrific demonstration of his invention.  The thing that really got my attention was that he told me that what I saw that day was only one of about 6 different kinds of wireless systems he has hidden in that property.  He said that he had 9 still cameras and 4 video cameras throughout the woods.  He started sounding a little weird and I felt a little uncomfortable so after he told me that nobody is allowed in there unless invited, I decided to leave.  

I know, this is getting long, but I thought that you guys would be interested.

I have gone back to that area several times looking for this guy to ask more questions without any luck.  I even asked in gas stations and resteraunts and some people told me they heard of him but they do not know him.  One guy told me that I wasn't welcome out there and that the photographer just might be one of those weird militia recruiters and some very strange things have happened in that area.  I haven't been back there for two years.

Does his system give any of you any ideas?  It might be fun to play with.
 



JoelM

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Hi Bald Eagle,

Was this in OHio? What part of Ohio are you from? I am in southeast part right on the border of Ohio and west virginia.

Cool story. Would be nice if you could find the guy again and get some more info though.

Keep me posted.

Joel
 

apittet

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Hi there,

Interesting story about your wireless friend in his computerized maze.

As you may have seen from my first posting to the list, I hacked also a wireless security motion detector for my first trail cam. The system uses a regular fresnel lens + PIR sensor followed by very low consumption opamps and gates.  Whenever a movement is detected, it generates a radio signal that sends off the ID of the detector (settable through dip switches). The whole thing runs off a 9 V battery that is supposed to last for a year. In a security system you have one such unit in each room and a master station that listen to the given frequency and decodes the ID whenever a movement detector goes off.

Right now I just hacked the PIR and did not make use of the RF signal, but this is in the “bigger picture” as we have a very peculiar requirement. For one application we need to take pictures of the animals (tigers) from both sides to ensure a 100% identification by analysing the coat markings (stripes). These are kind of finger prints for our tigers, but we need to get both sides for proper id … that’s life … and it is a bit hard to request them to turn around for the second pic ! Right now they use the expensive Trailmaster with wires dug up across the path to trigger the second camera. My plan is to have one movement detector with RF output and to build a simple receiver for each camera trigger. This will allow me to have a small delay ( a few millisec) between the two shots to avoid cross flash. When you think about it, such systems would allow you all kind of fun with as many cams and flashes as you wish … ideas are plenty, but time is in short supply.

More about it when it takes shape.

Cheers

Andre
 

Archilochus

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Sounds like an interesting & costly system he has going there!  I'd stay off THAT property - he might have some automated intruder disposal systems!

RF comms for trail cams is pretty easy - either buy a pre-made wireless sensor, or use one of the many RF Tx/Rx "modules" being offered for FCC license free use (in the USA).  My favorite is Abacom technologies < http://abacom-tech.com >

>>>
"
Apittet.... Here's another, less expensive, option for triggering multiple cams without wires.  Use "slave" flash triggers.  Hook them up as the triggers for your second (thrid,fourth...) cameras delay timer.  You can have as many "slave" cameras as you want.  Each cam would need a slightly longer delay to avoid cross flash.  Lots cheaper than RF and uses much less power on the recieving end (most RF recievers use from 1 to 6+ mA).  Range is about the same.  Only downside is you need the flash on all the time - not that that's a bad thing....

Good Luck!
Archilochus

Those tigers remind me of a line from a book.....
“Walk softly, stranger, for here there be tygers”.
 

ghoot

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Hmmm,
I wonder how he was sending the signal to his laptop and how far he could recieve the signal?  One step closer to getting pics at the office!
GHoot
 

Tinhorn

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A fewf weeks ago I bought a box of used smoke detecters that operate off 9v batt's but have Radio Xmitters in them.  I assume they transmitted to a main unit that told what Zone the detector was located in or maybe they were just "Chained Together" like a lot of Home Detectors are, only wireless. (when one goes off, they all go off)

I am hoping this last thing is the case,  because I was wanting to have several cams go off by a single PIR, when using the "Squeaker" to attract predators.

If chaining together is the case, I wonder how much the individual smoke detector costs, maybe an economical way to use multiple cams, like Andre needs to do......

Tinhorn
 

Archilochus

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Interesting idea Tinhorn.
I'm just guessing that the smoke detectors are "one way" transmitters only (no built-in receiver).  Like you said, each detector probably triggers a central alarm system - I'd doubt that the central receiver would then bother to send signals to all the individual detectors - it would most likely just set off a bunch of alarm sirens.
The main reason I assume this to be the case is that while RF transmitters use VERY little (or no) power in the "wait-state", the typical RF receiver uses several mA continuous - which would kill the detector batt mighty quick - even with clever power down cycling schemes.  That's why I suggested the slave flash triggers as "receivers" - they use just about zero power while waiting.

Arch
 

apittet

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Hi Arch,

I like the idea of using a simple slave flash trigger unit to let the second / third cam go off. Clean, simple, no power !  By any chace have you already done a post mortem of such a slave trigger? do you have a small circuit diagram? just curious ... also, in these few days on the list I already came to know that Arch seems to have tried already all what you can think about :smile-big-blue: Your "lab" must be a great place !

Cheers and thanks for the tips

Andre
 

bat

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Sounds like I need to revisit my old idea of using a duplex adapter adding to my phone connection.  Run the main camera off one side and run another wire off the other plug thru the purge valve to a secondard camera.....hmmmmm I got to set one of those up and try it out.  I know it works on the porch.  I would like to see both side of a deer sometimes to get a better look at his antlers.  :batwings:
 

Archilochus

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Hi Andre,
Wow! - never had anyone call it a 'lab' before!  Usually people refer to it as the 'dungeon', 'pit', 'hole', 'disaster area' or 'dump'  :-0

I have hacked open a slave flash trigger or two - unfortunately I never drew up a schematic.  They are very simple - just a sensor (typically a tiny 'solar cell'), an SCR, a capacitor and 2 or 3 resistors.  If I'm not mistaken, the capacitor and resistors help filter out lower frequency "noise" while permitting the fast photoflash light pulse to cause a trigger.  If I remember right - on the "hotshoe" mount slave triggers -  the "shell" (the part that slides onto the hotshoe clip of a camera) is the negative side, and the little contact in the center is the more positive side (I'll double check on that to make sure). When a photoflash is sensed, the 'solar cell' turns on the SCR, which 'closes' the circuit between the 'shell' and the little contact.
It's easiest to just think of the slave trigger as a "light sensitive relay" that closes a contact when a flash is sensed.  Hook the slave trigger up to your delay timer input the same way you might connect a momentary pushbutton switch.

I've had cheap 2.50US$ slave triggers set up out in the bright sun and never had a false trigger.  It's possible that some types of artificial lighting might cause problems.

I'll see what I can get done for a schematic, and maybe a few pictures of the units I built.  I'll repost to this thread when I have something done.

>>>>
Bat ..... Don't forget to add in some kind of brief delay - else you'll possibly get pics of the bright flash from the cam on the other side.  I suppose you could just aim the cams so they don't quite face each other....
>>>>

Good Luck!,
Archilochus
 

Archilochus

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Well... got off from work a bit early today, so I tossed a couple bits up on my not-quite(not-even-near-to)-finished "new" web-site.  I just put links to save some download time for those who aren't interested....

This is a schematic of a typical basic slave flash trigger.  When it senses a flash, it momentarily connects the "+" and "-" inputs.  Use appropriate resistors to limit current as needed for your circuit:
http://archilochus.netfirms.com/images/slvflash.gif

Here is a picture of the simple wiring & mono audio jack on the inside:
http://archilochus.netfirms.com/images/slvflin.jpg

And ouside with a cable attached:
http://archilochus.netfirms.com/images/slvflout.jpg

AEH ....  I bought these slave triggers several years ago at a "going-out-of-business" sale.  I think cheap slave triggers can be found on the 'net at around 4.50 to 7US$  I'll have to take a look around.

Archilochus
 

apittet

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Good and great morning !

Thanks a ton for the details. As usual once the idea is out I am wandering how I didn't think about it ! I was just wandering how the last pic will look if I have 5 flashes going off one by one around a Tiger ... it might be off the ground at the last one like in a cartoon ... the nearest disco is a bit far from their den !

Thanks again Arch ... now I have to work on it.
Cheers

Andre
 


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